One of the things I find really cool about Ingenuity is how it is in large based on consumer hardware. The main processor is a Snapdragon 801 running Linux which communicates with Perseverance using the Zigbee protocol [1]. Perseverance on the other hand uses a RAD750 from 2001! If successful I hope this can lead to more modern hardware for these kinds of missions in general.
As the name RAD750 indicates, that processor is designed to be radiation hardened which matters for longer missions. I doubt the Snapdragon 801 will survive as long or have as few errors but it also doesn't matter since Ingenuity isn't aimed for long term usage.
It’s less about longevity and more about reducing errors. Interestingly, Ingenuity has some sort of watchdog that can reset the Snapdragon in-flight fast enough to recover if there is an error.
A consumer chip is a lot more likely to be permanently damaged by a "silver bullet" cosmic ray, though. Rad-hard chips don't just have shielding, they can also have redundant circuits and modifications to the foundry process. That said, I'm sure Ingenuity's processor is fit to purpose.
Actually being stuck in the past might be a feature. Denser circuitry is likely to be more vulnerable to interference by ionising radiation and more vulnerable to physical damage from high energy particles.
Most of my knowledge of the subject is from a friend who did his PhD dissertation on it; specifically, triply-redundant adder circuits for single-bit operations, allowing for some rad-hard chip designs using regular foundry processes.
I mean its space. Any computer expected to be in space and do non completely trivial things have tons of mechanisms in place to survive computer issues.
Reminds me of Apollo 11, where the computer kept resetting on the way down to the lunar surface but still got Neil Armstrong and Buzz Aldrin to the moon with the whole world watching.
It wasn't resetting, it was ditching lower priority tasks that it didn't have (real) time to accomplish. Notably, the computer was still doing important work (ahem, flying the LM :-) ), and the tasks it didn't have time to do were not critical.
The team had recently seen similar failures in simulation, and was able to quickly decide it was okay to proceed.
> Notably, the computer was still doing important work (ahem, flying the LM :-) ), and the tasks it didn't have time to do were not critical.
I believe this is incorrect. From an earlier HN discussion:
"The 1202s were also a lot less benign than is often reported. They occurred because of the fixed two-second guidance cycle in the landing software. That is, once every two seconds, a job called the SERVICER would start. SERVICER had many tasks during the landing. In order: navigation, guidance, commanding throttle, commanding attitude, and updating displays. With an excessive load as caused by the CDU, new SERVICERs were starting before old ones could finish. Eventually there would be two many old SERVICERs hanging around, and when the time came to start a new one, there would be no slots for new jobs available. When this happened, the EXECUTIVE (job scheduler) would issue a 1201 or 1202 alarm and cause a soft restart of the computer. Every job and task was flushed, and the computer started up fresh, resuming from its last checkpoint. It was essentially a full-on crash and restart, rather than a graceful cancellation of a few jobs. And unlike is often said, the computer wasn't dropping low-priority things; it was failing to complete the most critical job of the landing, the SERVICER.
Luckily, the load was light enough that of the SERVICER's duties, the old SERVICER was usually in the final display updating code when it got preempted by a new SERVICER. This caused times in the descent when the display stopped updating entirely, but the flight proceeded mostly as usual. However, with slightly more load, it was fully possible that the SERVICER could have been preempted in the attitude control portion of the code, or worse yet, the throttle control portion. Since each SERVICER shared the same memory location as the last one (since there was only ever supposed to be one running at a time), this could lead to violent attitude or throttle excursions, which would have certainly called for an abort. Luckily, this didn't happen -- and the flight controllers didn't abort the mission not because 1202s were always safe, but because they didn't understand just how bad it could be, were the load just a tiny bit higher."
What I imagine for long lived and high-cost missions is using some sort of co-processor setup with a radiation hardened processor and a faster and more modern processor. These rovers run a lot of computer vision algorithms and I believe more powerful hardware would be quite useful. They may already do something like this, however my understanding is that there is a lot of skepticism in integrating these less fault-tolerant processors. Ingenuity could help remove some of the skepticism and lead to more systems like this in the future.
Do keep in mind that radiation cause permanent damages at predictable paces... I don’t understand why online discussions like this fails to address permanent damages. You can’t reset burnt chips.
I wonder if it wouldn't have been possible to do this on Perseverance too. After Ingenuitys mission is done they could have lugged it arround for extra processing power for as long as it survives. I doubt the extra weight causes that much extra energy consumption.
The software stack is probably not ready for that since the plan is to abandon it after its mission. And the Zigbee protocol is rather limmited.
One thing that's not clear to me is what the radiation is like on mars. Mars has an atmosphere, but no magnetic field.
Is it like the situation high in earth's atmosphere (like using your ipad on a commercial flight), or would it be more like on the moon with no protection?
Between the two. 30 µSv per hour on the surface of Mars on average compared to 60 µSv on the Moon - compared to 5 µSv on a jet. Not friendly, but not too awful.
Or 0.5 per hour on Earth at sea level. That's only 2 orders of magnitude difference. Given that we don't expect radiation damage to be a major source of failures in Earthbound consumer or commercial electronics, it's a bit surprising it's such a big deal in space.
The composition of that radiation is important - Earth's atmosphere preferentially filters out a lot of the higher-energy particles that are likely to permanently damage electronics. The sievert as a unit is weighted based on damage to biological systems, not electronics.
Well 2 orders of magnitude can turn a problem that occurs once a decade into a problem that occurs once a month so it's not too surprising that the problem is a bigger deal in space.
There are actually a lot of bit flips in Earthbound electronics due to lack of parity error checking. But those bit flips don't necessarily cause failures, or when they do it's impossible to determine the root cause.
yes but these chips having to function and survive on the way to the planet right? and they do all sorts of software updates etc during this time. Maybe we could shield them and that would be fine? or would that add to much extra weight
They work better primarily because they had previously invested in the tooling to rad-harden them and it’s really expensive to do that again one time for each mission; cheaper to rely on already-rad-hardened designs.
Just an example: consider you were to add some extra electrical charge to the gate of a transistor (from an electron or ion beam, I don't know).
A larger transistor has a higher gate capacitance, it is therefore quite immune against a few extra charges. On smaller transistors, though, it could dramatically increase the voltage, leading to a bit error, or destroying the transistor. Capacitance in this case is proportional to the area.
Higher density also has some inherent drawbacks against particles, since a damaged part is proportionately more damaged if it is smaller.
More ancient processes are also higher-voltage, and higher-current, so they can handle a lot more noise on these signals.
I believe the reason is that volume is too low. The radiation hardened chips for Curiosity and Perseverance are variants of Power chips made by BAE.
I am surprised though that they have not released any newer chip in time for Percy. There is a newer generation, the 5500, but I believe it was not ready for Percy. Percy uses the same chip as Curio.
That's one way of doing it. But making bigger integrated circuits (IC) is hard. And it wouldn't automatically give you increased performance.
In microelectronics, costs are directly proportional to the die area. Actually, they might rise faster due to yield issues.
Making masks [1] is expensive. The bigger the mask, the more expensive. A mask set for a modern CPU can easily be in the millions, I think. And it gets more expensive with size.
Then you have yield. The bigger the chip, the more likely it has some defects (due to dust or other issues during fabrication). Often, processes work more or less well across a wafer: temperature higher in the center, etc. That can affect performance.
Due to yields, bigger chips have to be scrapped more often, and are generally less performant. Binning (selecting the fastest, slowest, more efficient, or chips with specific intact features across a wafer) is less effective. You might have to add redundancy or mechanisms to cut power to damaged areas to avoid short circuits.
Now, that's why we don't generally make bigger integrated circuits. Now, we could make bigger integrated circuits with today's latest clean rooms and equipment to try to raise yields. I don't know if that's being done already, but it would likely raise costs. On the other hand, progress is being made on bigger chips as well [2].
Another more promising direction (IMO) is to use chiplets like AMD does it. You could use more of these for a bigger virtual size.
Now, like I wrote, a lot of the performance improvements actually come down from physically scaling down the transistors: if the gate is smaller, the transistor needs less electrons to charge up. That means faster transistors, and less energy. Also, transistors are closer, so signals reach the next one faster [3].
If you want bigger chips at a previous technological node, you are going to need a huge heatsink, or disable part of the chip ("dark silicon") [4].
The real answer might come from completely different architectures, based on light or spin, or more power-efficient circuit/computer architectures like with adiabatic computing [5] (or non von neumann based, closer to what I do).
Power efficiency is key, since that's the limiting factor for performance nowadays (ask any overclocker: you don't want to melt your CPU. Also, rovers have a small energy budget). With better efficiency, you have room to grow performance again.
Paradoxally, software seems headed in the other direction, generally speaking.
Doesn't radiation mostly cause random one-off errors rather than permanent defects? If so, then if the rad-harden stuff is 100x slower (which I think is approximately right?), it is almost certainly better to use error correction on non-rad-hardened hardware.
Many types of bit error are not recoverable without a full system reset. It isn't a matter of a simple "this bit in ram got corrupted", but more "this floating point unit has got into a state where it will not produce a result, and will therefore hang the entire processor".
Therefore boot time becomes critical - if you end up rebooting due to bit errors multiple times per second, you can't afford to wait for Linux to start up each time...
And that’s why it’s wise to have multiple systems running at the same time, if one errors you still hopefully have another online. There’s a reason airplanes and now cars are designed this way. I’m sure they’re working towards this too.
This is a problem with floating point operations happening at a lower level than the error correction you're imagining. In principle, that's not at all necessary. Are you arguing that it's infeasibly expensive to design a chip with operations that are error correctable?
These projects also have long development periods, they want to be sure everything works so they can't just sub things out at the last minute. So you end up with a system using 10 year old tech.
https://media.ccc.de/v/36c3-10575-how_to_design_highly_relia... is a really interesting talk by some guys from CERN who have to design chips for use in particle accelerators and other physics experiments where they must survive unusually hostile radiation environments.
It's trickier than it seems because some forms of radiation can induce different kinds of radiation when they hit the dense shielding so you're kind of back to square one in that you still need a radiation resistant processor.
If you were to build the exact same helicopter here based on those parts what would be the cost vs what’s the device on Mars cost? Also, I know plenty of solid engineers who I could build one thing based on that, obviously not taking atmosphere and G-forces into account to get there.
Also Linus finally got his progeny to Mars. That’s a pretty cool accomplishment:
“What have you built?”
Well, I invented one of the most prolific operating systems the world has ever seen, but not just this world - there is a helicopter on Mars that is flying due to the seeds which I planted that day...”
It's not just atmosphere and g-forces. The cold temperatures mean the helicopter spends 2/3 of its battery power keeping the batteries and electronics from freezing.
One of the fascinating things about space silicon is that NASA spends many years hardening specific processors to withstand the types of shocks and electromagnetic interference from space travel. These intensive processes mean that the equipment they can use is always 10-20 years behind the modern equivalents.
Aren't smaller transistor sizes also more susceptible to radiation issues which means you can't really use newer processors without ever more effort in radiation hardening?
But then you have to build for redundancy rather than just performance (say, sacrifice some floor-plan to error correction, recovery, circuit duplication, etc...)
> Ingenuity runs Linux (for the first time on Mars) and uses the open-source F' software framework on a 2.26 GHz quad-core Snapdragon 801 processor. Radiation hardened processors aren’t fast enough for the real-time vision requirements of the experiment—but as an unprotected COTS processor, it will fail periodically due to radiation-induced bit flips, possibly as much as every few minutes. NASA’s solution is to use a radiation-tolerant FPGA ProASIC3 to keep an eye on the CPU (paper) and software that attempts to double-check operations as much as possible. “[I]f any difference is detected they simply reboot. Ingenuity will start to fall out of the sky, but it can go through a full reboot and come back online in a few hundred milliseconds to continue flying.”
I would be interested in seeing what they did to get Linux booting and their userspace daemon running in ~300ms or less. Depending on their non-volatile storage read rate, using an uncompressed kernel might not actually save boot time. I'm guessing they aren't running traditional init or systemd.
I've been told LinuxBIOS is able to get you a text console login prompt faster than hdd platters can spin up, but it takes Ubuntu tens of seconds on my SSD laptop to get me a login prompt.
I'm surprised they don't have an FPGA MEMS autopilot with a simple degree 2 or 3 polynomial model of the flight dynamics , with the CPU and Linux only being involved in making adjustments to the autopilot. Or, maybe that's what they're doing, and by "falling out of the sky" what they really mean is the autopilot drifting.
The CPU will probably be destroyed by radiation before long. I'd guess the key factors here were weight, power draw, size and perhaps performance. A radiation-hardened CPU probably didn't fit the bill. It's also super expensive.
Any individual part is peanuts compared to overall mission cost. Anyway, it’s a great PR stunt for QCOM. It’s not that big secret, that cubesats successfully use automotive grade off shelf parts.
absolutely performance. Yes to the other three for sure, but the engineers reported that there was no way they were running flight control using image tracking on a 200MHz CPU.
Not in python, maybe. Smartbombs have been doing the necessary image processing with much less processing power, on much less capable sensors, for a long time.
Dunno about guided bombs, but cruise missiles have been using some pretty fascinating techniques to navigate before GPS was a thing. It's probably hard to find CPU specs, because they're defense technology.
It is surprisingly easy to find, as that stuff is pretty thoroughly covered in academic/industry journals. The only hinderance to access is a credit card number for the paywall.
The helicopter project is somewhere said to cost $80 million.
Would be interesting to know cost allocation for that Sony/Samsung chip. Project manager and scientists/engineers could have listed design challenges for industry player like TSMC/Apple go beat with an offering, a short run of 20 chips specifically for this helicopter.
What. I dont understand how you can make this claim. Guided bombs are NOT using CV with optical cameras. They use lasers, GPS, and other non "fancy" techniques.
I just don't get in what world you think military munitions are using CV for targeting bombs.
So I guess you've never heard of the AGM-62 Walleye, or anything else that came out of China Lake. Before you try backpedaling with some silly nonsense about how gating isn't real CV, maybe do a quick search through the journals that cover this stuff: aiaa would be a good start. Another path would be in relation to counter-counter-measures, and ground noise rejection for air-to-ground radar guided munitions. That stuff was deployed regularly all the way back to Vietnam.
The other poster mentions analog techniques used in contrast-tracking TV-guided munitions like the Walleye, but digital "CV-like" image/contour matching methods were used on the original Tomahawk cruise missile and the Pershing 2 missile to provide terrain-matching navigation and target guidance. GPS was neither sufficiently complete or accurate for strategic weapons in the late 1970s/early 1980s.
In more modern weapons, imaging IR sensors are well-established for terminal guidance on missiles like LRASM, JASSM, or NSM to distinguish targets from clutter and identify specific target features (specific parts of a ship, for example). Of course "traditional" "IR-homing" SAMs and AAMs now use imaging sensors (often with multiple modes like IR+UV) to distinguish between the target and decoys/jammers. Even your basic shoulder-fired anti-tank missile like Javelin requires some amount of CV to identify and track a moving target.
aka edge detection :) I don't remember if it was the Sidewinder or Walleye that eventually dropped in a CCD (or both), but I know that the Maverick (which is technically older than Walleye) got along without a CCD until the GWOT - when it finally upgraded. The Javelin actually beat Maverick in that regard, having a 64x64 sensor 10 years earlier - able to handle scaling and perspective change for the 2-d designated target pattern.
It seems other parts are more modern. Yes, the main processor is a RAD750, but the peripherals can use modern components and there's some USB and Ethernet here and there (like the cable between the sky crane and the rover)
Reliability is very important and space is harsh. I assume on the surface the radiation levels are low enough for Earth systems to work (maybe playing a bit with voltage/clock frequency helps, not sure how much shielding they can add, probably not too much).
The problem is that NASA is designed around long term and expensive projects.
At one point, a fast iterating company like space-x will surpass their achievements.
Why would SpaceX bother doing science, though? If you imagine a project like Voyager, you might think they just dump the data and "go home" (not quite, obviously) but to analyse the data and to know what to look for they had to hire geologists and meteorologists (for example) along with the planetary scientists and co.
NASA should be about long term and expensive projects, SpaceX is just a tool to achieve that goal which is to do new science regardless of whether it is in the air or in space.
Fun fact: This is not the first time a space program has flown on another planet. The Soviets launched weather balloons on Venus during the Venera missions [1]
And given the density of Venus' atmosphere, here is a fun thought experiment.
It may be possible to make 'titanium' balloons for longer term operation. The would work by creating the balloon envelope on earth, have a sealing mechanism that you activated in orbit so they had vacuum inside. And then drop them into the atmosphere.
Same idea a glass floats on fishing nets[1] except with titanium (so they can withstand the compression forces given they have a vacuum inside). It might be useful/necessary to put some additional structure inside the envelope for strength but like eggs, the sphere is a pretty good shape for distributing compressive force.
Anyway, put a number of them on tethers attached to the instrument payload and drop it off into the atmosphere once you've gone trans-sonic with parachutes or retro rockets. The platform will then fall to the point where the lifting force of the floats is equal to the weight of the platform.
Ideally the titanium would be impervious to the atmospherics's corrosive effects.
The challenge is that Earth's air isn't dense enough. That said, the math is "easy" density is volume/mass, vacuum adds no mass, so it is just material mass / volume.
A 20cm diameter diamond sphere that was .5mm thick would have a mass of about 41g, a 20cm diameter sphere of air at sea level and "room" temperature is about 50g. So you would get 9g of "lifting force" from such a balloon (assuming I did all the calculations correctly). And experience about 2,900lbs of compression force.
If you're interested in some fiction with this concept: In Neal Stephenson's 'Diamond Age' humans have mastered assembly of individual atoms in basically arbitrary ways. They use it (among other things) to create flying airships with an envelope made of diamond with a vacuum inside. Found it to be a fun read in general.
I've really enjoyed several of Stephenson's books, but 'Diamond Age' was one I couldn't get into. I need to give it another shot.
On the subject of Sci-Fi, there's also a vacuum airship featured in one of Edgar Rice Burroughs' Tarzan novels - 'Tarzan at the Earth's Core'. It is of course much less scientific than Stephenson's version though.
He really likes to drop readers in with minimal explanation into a world, he's gotten much better at it over time but Diamond Age is both one of his earlier works and one of his most esoteric worlds with the odd neo-Victorians etc.
That's always a fun blast from the tech hype past where nanotechnology was going to be pure magic with tiny machines capable of doing anything. That was an exciting possible future while it lasted, nanotechnology is doing neat stuff but it's nowhere close to the wild promises.
Yeah we're starting to do that but the individual pieces are pretty large and I think we're much more level headed about how small they can be shrunk now.
This is a plot element in Neal Stephenson's The Diamond Age, as well as several other fictional appearances (Edgar Rice Burroughs, Azhar Abidi, Peter Watts, and Iain M. Banks all use the trope).
There are no materials known with sufficient strength to withstand compressive and buckling forces. Not even diamond.
Lightweight stiff structures (honeycomb, something resembling aerogel, perhaps) are other options, but seem unlikely as well.
Gas-filled airships or balloons benefit from the fact that low-density gasses (by either chemical composition or temperature in the case of hot-air balloons) exert a countervailing pressure to balance atmospheric pressure, but with a lower mass, hence providing buoyancy. The internal pressure actually provides some (or much) of the structural rigidity of most airship variants. Any vacuum airship would have to make up for this factor, again, increasing strength (and material mass) requirements.
I am following https://www.o-boot.com/en/ with interest. They claim to have solved the buckling issues by using a roman arch-like structure.
The idea sounds relatively sound to me. One could construct a sphere out of aerogel cones, and the external pressure would reinforce it. Not sure how practical it would be to build such a thing, though.
s/since volume grows slower than volume/since surface area grows slower than volume/
Square-cube law. Mass scales with surface area, lift scales with volume. Large balloons (conventional, not vacuum) are simpler and more efficient than small ones.
As to materials, a tremendous problem with areogels are that they're exceedingly friable. Any friction, flexing, or stress will crumble the gell to a powder. I suspect this is why the gel hasn't taken off as it had been projected to. I did some very-early 1990s work in the space and aerogels were a noted emerging technology thought to have applications in, e.g., mobile home, pre-fab housing, and RV designs. For the most part, fibre-based insulation or expanded-foam (polystyrene) insulation remains the standard, largely because road and other vibration don't reduce your insulation to a few inches of fine dust at the bottom of wall cavities.
Material properties are complex, and represent interesting trade-offs between afforded capabilities and imposed constraints.
Venus’s atmosphere is 100x denser than earth’s, so you could just seal the metal balloons at sea level pressure and it wouldn’t really make a difference. Or you could seal them in a vacuum on earth. Not sure why you would need to feel them in space.
Weight and volume. The air has weight so it'll cost more to launch. The volume would also make them more difficult to launch. Assembling or unfolding in space near earth would allow you to make them larger and inspect them before they leave for venus.
Oh I like that idea! Tricky to get it through the deceleration phase into the atmosphere but it would have a lot of volume. You would want some way to detach the engines (less mass) after you slowed down while still sealing the tanks.
Yes, but you could still construct it in orbit. Imagine building four quadrants, spooning them together for launch, then fusing ("cold welding") them into a sphere in space.
It is surely better to construct them here, where we have all our tools, and if really necessary pump them out here. There just isn't an advantage to doing it in space. You end up paying more to create a lower-quality sphere.
And what weighs more - the air that got trapped in the sphere when we made it, or the machine we sent up to space to assemble a sphere there?
On the Moon the first controlled powered flights were likely the Surveyor and Luna probes - they had braking and landing thrusters controlled by onboard avionics.
I'd argue Mars is still the most impressive. Rockets in no atmosphere is easy. Floating on Venus is easy because it has more atmo than any other rocky planet.
Figuring out something that works well in Mars' thin (but still there) atmosphere, especially a helicopter, is really impressive. The celestial body classification is just a cherry on top.
By many definitions the Earth-Moon system is a dual planetary system. The moon has more that 1% the mass of the Earth, which is by far the largest primary-secondary "not a planet" system in the solar system. Only not-a-planet Pluto and Charon exceed it.
Also, Isaac Asimov considered the system a dual-planet system as the Moon's path around the sun is at no point convex nor retrograde.
> Earth-Moon centre of mass is inside Earth, so, it's
> obvious that the Moon is orbiting the Earth, not both
> orbiting something else.
I used to agree with that school of thought, until I came up with a small thought experiment. Consider two bodies that are right on the planet-moon / dual-planet definition threshold. Intuitively, increasing the orbital distance between them would push them in the direction of which definition: planet-moon or dual-planet?
I'd tend to say that separating them further would tend more towards planet-moon. Yet doing so moves the system's center of mass outside the larger body, so would actually push the system into the dual-planet definition by that criterion.
It's a fun exercise to work out the Gravitational Force between the Moon and the Earth and between the Moon and our Sun. It will surprise many that the Sun exerts more force on the Moon than the Earth does. So the Earth inflicts a strong perturbation on the motion of the Moon but it's not the dominant gravitational force on the Moon.
If we understand "flight" as being the use of a wing to generate lift in an atmosphere, then I think we can safely say this is the first time we have flown on another planet. I assume this little helicopter actually has rotary wings rather than fans.
The first powered flight was in 1903, with the criteria that it was not gravity assisted, that it was sustained and that it was controlled. No one is claiming that it was the first flight ever.
Lighter than air is flight - one cannot say dirigibles and hot air balloons are not flying machines.The distinction is made between lighter than air and heavier than air - for which the first was success was by the Wright brothers.
If we're splitting hairs then the lack of control seems like a better criterion to distinguish the two. If you ask me there's no reason a zeppelin would be inherently less 'flighty' than a helicopter.
In the space industry, “flight” is used for all types of vehicles so I’d also argue to use that very broad definition rather than terrestrial terminology.
The term used in the article was “powered flight”. This distinction is relevant in the history of aviation on earth as well, and usually that term is used.
For sure the soviets did some neat science work but I think a motorized helicopters flying on Mars is pretty darn cool too compared to a ballon floating in a dense atmosphere it even feels like an advancement
It's actually not even the first time a powered aircraft has flown on Mars. Both Curiosity's and Perseverance's descent stages were powered aircraft that, after releasing the rovers, flew up and away from them in a controlled manner through the air.
A solar drone that takes hours to charge and flies only a minute at a time is barely an aircraft too. Don't get me wrong, it's a very cool tech demo and I can't wait to see the video, but IMO if your goal is to take pressure/composition measurements in the atmosphere at a variety of altitudes, a weather balloon is the right tool for the job.
Nobody is arguing that it isn't the "right tool for the job". Just that a balloon isn't an aircraft. While a drone that flies for a minute at a time clearly is.
I didn't realise it was so large (1.8 kg, 1.2 m diameter rotors). I suppose it has to have the large rotors to be able to generate lift in the thin atmosphere, 1/160th of the density [edit: pressure, not density - thanks Robotbeat] of the earth's atmosphere at sea level according to the article.
Turns out it’s not quite so bad. 1/160th the pressure doesn’t mean 1/160th density because CO2 is denser for the same pressure, especially Martian temperatures. And Jezero crater is much lower than Mars “sea level.”
This apparently also introduces some serious control issues - with propellers that long and massive, there's substantial lag between control inputs and flight changes. In ground tests in pressure chambers, it was difficult-to-impossible to manually pilot the thing, and even under computer control it's very clearly shakier than Earth-atmosphere drones.
Wow, I never realized it might be 160 times harder to get off the ground on Mars. Perhaps lower gravity helps on the other hand, though the difference definitely seems way lower (please correct me if my physics is wrong).
>One of the most significant obstacles for landing on Mars will continue to present problems for our heroic helicopter now that it is safely on the surface. The atmospheric pressure on the surface of Mars is only about 1% that of Earth. To put that in perspective, the summit of Mount Everest has only one-third the atmospheric pressure of sea level. While this is thought to be at (or sadly in some cases beyond) the limit of what humans can survive, it is well beyond Earthbound helicopters’ range. If you’ve ever wondered why wealthy explorer-types don’t just cheat and take a helicopter to the summit of Everest, that’s why!
Ummm... actually:
>On June 21, 1972, Jean Boulet of France piloted an Aérospatiale SA 315B Lama helicopter to an absolute altitude record of 40,814 feet (12,440 m).[60] At that extreme altitude, the engine flamed out and Boulet had to land the helicopter by breaking another record: the longest successful autorotation in history.[61] The helicopter was stripped of all unnecessary equipment prior to the flight to minimize weight, and the pilot breathed supplemental oxygen.
>The record was broken on March 23, 2002 by Fred North. North achieved an altitude of 42,500 feet (12,954 m) in a Eurocopter AS350 B2.
It should be clear that while Eurocopter and Aerospatiale before them liked showing off specific modified helicopters in the Himalayas (up to and including landing on Everest), none of them were capable of carrying a useful payload to that altitude. Helicopter altitude records are much like zoom-climb records in jet aircraft - yes, you can reach those altitudes, but not for long and not while doing anything else.
I am incredibly excited for this. Can believe how nervous the control engineers must be for this. Not sure what quality of the footage to expect from this.
I was also excited about it, however an article critical of various points of Mars 2020 damped this quite a bit [1 (in German)]: Does the drone actually have any scientific relevance? I'm even doubtful it answers relevant engineering questions. I mean, it was tested in a pressure chamber already simulating mars atmosphere and gravity, we know it will work. The only question seems to be: Will it fail because of some engineering oversight or hardware failure, or not? There seem to be no scientific sensors on it at all. This 'commodity hardware test' could also be done with just the processor and monitoring, without the helicopter part. Looking at it like this it seems like mostly a toy or PR stunt, but one that takes $80M and space on the rover away from scientific projects.
I do not agree at all that it is not useful but even if true the PR in itself is likely worth it, both for getting more attention to NASA (IE. budgeting) and for sparking ideas and dreams.
I'll gladly change my mind, what is it useful for?
On your other point, I'm sure many people find it fascinating and are inspired. However a young geologist or biologist might not be inspired to start a career at NASA. Another point the author of the article above makes it that in the ~2 hours of live coverage, 6 seconds were spent discussing the rovers instruments.
As for budget, this is also dangerous; after all, if the next funding round comes along, anyone who does not like NASA can have an easy argument that the $80M on the helicopter are wasted and did not produce any knowledge about Mars or the universe.
It's useful (if it doesn't die) for scouting. From above, it will have a better look at the terrain, helping mission control do path planning and terrain/risk assessment. I have no information telling me that's going to happen, but this is my fairly educated guess as to how the drone could be used.
Ok, that could be a use for it. They do have satellite images, but I guess those are much lower resolution and a better satellite would probably be orders of magnitude more expensive.
Sadly, this helicopter won't record any footage, it is only meant to test flight control and to proof that the idea will work for future missions. There is a interesting Veritasium episode (youtube) that talks about this (interviewing the actual designer from the JPL). The only footage will be from Perseverance filming the flight.
This is not correct, there are multiple downward facing cameras [a]:
1) Navigation (NAV) Camera. This is a global-shutter, nadir pointed grayscale 640 by 480 pixel sensor (Omnivision
OV7251) mounted to a Sunny optics module. It has a field-of-view (FOV) of 133 deg (horizontal) by 100 deg (vertical) with an average Instantaneous Field-of-view (IFOV) of 3.6 mRad/pixel, and is capable of acquiring images at 10 frames/sec. Visual features are extracted from the images and tracked from frame to frame to provide a velocity estimate.
2) Return-to-Earth (RTE) Camera. This is a rolling shutter, high-resolution 4208 by 3120 pixel sensor (Sony IMX 214) with a Bayer color filter array mated with an O-film optics module. This camera has a FOV of 47 deg (horizontal) by 47 deg (vertical) with an average IFOV of 0.26 mRad/pixel.
One of the stated goals is to use of the drone to scout interesting places for other drones. In theory I guess it could take that decision without sharing the source images, but that seems a bit far fetched. You'd want to study them in ridiculous detail.
> Its payload is a high resolution downward-looking camera for navigation, landing, and science surveying of the terrain, and a communication system to relay data to the Perseverance rover.
The problem isn't the camera, it's the uplink to Perseverance and all the other parts required for a usable camera. They're using Zigbee [1] to communicate with the Rover at 200 kbps and the solar panel recharging the batteries also have to power heaters to keep the electronics alive - there's no hardware connection between the two for data or power exchange AFAICT. The drone is already so heavy that it can only stay aloft for 90 seconds to a few minutes between charges so between the extra battery, lens, better antenna and RF module, etc. it'd require a redesign of the entire mission.
It's not that heavy, relatively speaking, it has to spin the rotors a lot faster to gain altitude in 1% atmosphere of Earth, hence the shorter flight time.
The Snapdragon CPU has plenty of power for JPEG encoding and likely even hardware accelerated encoders. The 640x480 8bpp navcam images could be entirely usable at a fairly lossy 40:1 compression ratio which ends up about about 8KB per frame, for a 90s flight recording at 10fps that's only about 7.2MB to record the whole flight. It would take a little under 5 minutes to send that back to the rover at 200kbps. The color high resolution camera isn't set up for high frame rate recording IIRC so that was never an option.
High quality 30fps video was never really an option but it's entirely possible/likely to get navcam video after a flight. The Snapdragon is also fast enough to do intraframe compression codec (even h.264) for the navcam video to be able to stream it live back to the rover for relaying back to Earth later like was done with the landing imagery.
The nature of Perseverance relaying through orbiters for high speed uplink to Earth was always going to preclude "live" video from any instrument. The only data important enough for "live" transmission is vehicle telemetry and even then that's only available for the portion of a sol (Martian sidereal day) that Earth is visible from the rover.
I wish we could fund NASA more, make it more risk tolerant, more agile, and more efficient. The Titan boat drone to explore the lakes, last I heard, couldn't be scoped due to resources. Working there requires great patience.
> I wish we could fund NASA more, make it more risk tolerant, more agile, and more efficient. The Titan boat drone to explore the lakes, last I heard, couldn't be scoped due to resources. Working there requires great patience.
I wonder if funding NASA more would mean that the "inventive" ideas get reduced. The limitation of NASA's funding has meant that they've produced ideas and technologies to cover that shortfall in even cheaper ways than possible before, and that might be reduced with a much large budget.
I believe so. Funding competitors would likely yield better results, unless one is looking for US results versus results overall of course. A lot of very exciting missions are from other space agencies these days, which is great!
I haven't seen anything on specific timing but I read they will be looking suitable terrain (flat with no large dangerous rocks, but enough small rocks for the helicopter's vision system to register) to fly in as the rover drives. There's also no provision for the rover to pick the helicopter back up as far as I know, so they will be stuck in the same place during the 30 day test campaign. Given that and given the "proof of concept" nature of the helicopter I imagine there might be a desire to start getting data back from the rover's main scientific instruments before deploying the helicopter.
Is the plan to hide Perseverance behind a hill or something in the event the flight becomes uncontrolled? Last thing they need is a flying blender slamming into it...
Kinda curious those "pointy counterweights?" near the hub of the rotors, why are those there? Looks like they'd run into each other? It looks like it has full collective/cyclic on both levels.
Not sure about the counter-weights, but without a tail rotor, I'm pretty sure it requires either a collective on both levels, or else software to navigate properly when the body is spinning, and some mechanism to allow it to safely land while the body is spinning.
The torque to spin the rotor changes with the blade angle, so to keep the counter-rotating torques balanced, they need to control blade pitch on both. I suppose the blade drag is a non-linear function of blade angle, so technically they might be able to keep the torques balanced with cyclics on both and a collective only on one, but it's certainly much more simple to have at least collectives on both.
Oh, I'm pretty sure you want them spinning at the same speed so their angular momenta cancel out, in case a wind gust puts a torque around a horizontal axis on the system... cross product of angular momentum with applied torque...
One of the most significant obstacles for landing on Mars will continue to present problems for our heroic helicopter now that it is safely on the surface. The atmospheric pressure on the surface of Mars is only about 1% that of Earth.
Does this also limit the use of parachutes on Mars, or require bigger canopies? I know that Perseverance had a parachute for part of the descent, but not the final landing sequence. IIRC one of the earlier probes was designed to bounce rather than gently floating down.
Both, but the main limit of a parachute is that our probes don’t go into orbit first but rather crash on Mars.
So you enter the atmosphere at higher than orbital speeds. From orbit a parachute might be doable despite the relatively thin atmosphere.
Stationary probes can use retro rockets to land because you don’t care about their stationary mass that much.
For rovers it’s more tricky so you have to either use airbags like the smaller rovers did or a propulsive landing like Percy/Curiosity.
The sky crane was chosen as the method for those because they are too massive to do a cushioned crash landing and they won’t be likely able to move with the weight of the propulsive landing system so we have to ditch it.
The sky crane is basically the worlds most expensive bungee jump.
The rockets on the sky crane bring the rover to hover and then it drops to the ground on a set of arresting cables.
> Both, but the main limit of a parachute is that our probes don’t go into orbit first but rather crash on Mars.
So you enter the atmosphere at higher than orbital speeds. From orbit a parachute might be doable despite the relatively thin atmosphere.
> So you enter the atmosphere at higher than orbital speeds. From orbit a parachute might be doable despite the relatively thin atmosphere.
Nonsense. We send orbiters to Mars all the time, often on the same missions as landers. We could absolutely brake to orbit first (which is almost free via aerobraking) before dropping landers, but it wouldn't make any difference to being able to use parachutes, the velocity difference is insignificant.
Getting into orbit for a lander means you need a much higher transit mass to include fuel and rockets capable of slowing you down.
The Martian atmosphere isn’t thick enough for this kind of aerobraking especially if want to get there within a relatively short period during the transit window.
Yes we do send orbiters and these have to be smaller and so are their landers due to you having to slow down to get into an orbit first. The vast majority of landers do not get into orbit.
> The Martian atmosphere isn’t thick enough for this kind of aerobraking especially if want to get there within a relatively short period during the transit window.
Nonsense, once you've made your capture transit is over, you can take as long as you like aerobraking to circularise the orbit.
Even if you don't aerobrake at all, delta-V from a Mars intercept trajectory to even a low Mars orbit is about 1.4 km/s. Delta-V from that low orbit to the surface is 3.8 km/s. So the idea that direct descent vs descent from orbit is what makes the difference between parachutes being usable or not is total bollocks.
Going into orbit first would require a significant amount of extra fuel to decelerate and circularize. Heading straight into the atmosphere means more mass can go into the rovers instead of into fuel. It's a trade-off.
Yes indeed. Mars entry, descent, and landing (EDL) is hard. On Earth it’s easy: we can use the thick atmosphere to decelerate to a gentle drop into the ocean. On the Moon it’s easy: the minimal gravity makes powered descent feasible. On Mars it’s hard: too much gravity for an easy powered descent, too little atmosphere for an easy aerobraked descent. Larger spacecraft such as Curiosity and Perseverance (sky crane) and Spirit and Opportunity (bouncing air bags) have to get creative.
Thanks for your reply. I never thought a NASA engineer would answer me, but one of the things that blows me away about this community is truly knowledgeable people are participants in discussions and often weigh in.
Yes it does. The parachutes are unable to slow down the probes to a soft landing - they would have to be extremely large, which would make it even more heavy for landing. The large parachute on Perseverance slowed down the entry module to about 200 mph (321 km/h) which is not enough. Perseverance has a weight of 2,260 lbs (1,025 kilograms). The Mars Exploration Rover (Spirit) used parachute + retrorockets + inflatable airbags, but it weights only 408 lb (185 kilograms).
Most importantly it's use case of a helicopter, to prepare to the dragonfly mission at proposed 2036. One only hope for the bandwidth at the level of perseverance, it's 16 times farther after all.
All that does is complicate the already complicated EDL phase by an order of magnitude.
Trying to launch a drone from the lander during descent would mean:
1) the drone is able to begin its power up process at the end of the cruise phase while the whole probe is buttoned up for reentry
2) the drone has a big enough battery to power avionics, comms, component heaters, and the motors
3) the drone carries a big enough radio and antenna to at least reliably communicate with one of the orbiters relaying data from it and the main spacecraft
4) there's a at least one orbiter positioned to receive data from the drone and the drone manages to perfectly aim its highly directional high gain antenna at the orbiter after an unknown launch position and orientation
5) everything goes perfectly with the drone and it doesn't collide with or damage the sky crane or rover or debris from its launch (or failure) doesn't damage anything
Saying it "increases risks" with the landing is a vast understatement.
Given the weight of the craft and thin atmosphere, I would be surprised if there was any noticeable surface disturbance anytime outside of takeoff/landing.
Atmosphere is required to carry the energy that would cause disturbance. With no atmosphere, there are few molecules in the space around the copter to transfer the energy to the surface.
Phase 1 of the landing used parachutes to bleed off speed, but they aren't able to slow it enough for a soft landing. So a Skycrane was used for the second phase / touching down.
The blades on Ingenuity are larger (relative to the rest of the vehicle) and spin much faster than would be required on Earth.
I'm not sure that the drone has an uplink. If not, it would have to relay images to the rover over a 200kbps zigbee connection for transmission. Unlikely to be video in that case, more reasonably highly delayed still frames. Would be more in line with its mission profile as well.
I don't understand the point of all this business of learning trigonometry when there's all these history books to read!
Relax, we can and should do both. In fact, the various space programs have been immensely useful in terms of the technology we can apply right here at home and we learn stuff about our neighborhood. The more big, bold science and engineering we do the more our species benefits.
Watching the PBS NOVA series “Finding life on Mars” I am so proud to see such an astounding diversity of ethnicities involved in the Mars 2020 projects. I can’t phantom any other countries would have inclusively included other ethnicities in such a high profile project. Despite so many set backs in 2020, the US is still the most inclusive country at least in science and research.
Ethnicity isn't always visible. Just because a crowd of, for example, Indians or Qatari look the same to you in a command center video doesn't mean they're all alike or that the whole range of identities on the program are in that room at that time.
Have you been at the ESA stations in Europe. Lots of diversity there. Even in Russia you have loads of foreigners working.
About China I am not so sure though
Why is nobody worried about the helicopter crashing to the rover and possibly destroying a science instrument? How far will the helicopter be from the rover?
I’m pretty sure this was one of the main criteria for building the helicopter since the -reject is not essential to the mission but is instead is a demonstration.
It’s probably also why they’re waiting to fly it so that the rover is a bit further away
> If those helicopter blades spin 40x faster than a real chopper at sea level air pressure on earth, the turbulence alone would disintegrate the flywheel and blades and destroy the whole thing. So how did they test it?
The obvious method would be a large vacuum chamber, evacuated enough to simulate martian atmospheric pressure.
Your post was sneering at the idea of it being real, and I generally don't click on video links without a clear idea of what they are (because video is a low-information-0er-time, high-emotional-engagement medium, and experience has proven that it's almost never worth doing) and I'm even less likely to do so with the implied content from the rest of your post.
AVR = Augmented Virtual Reality. It's like CGI on steroids, crack, and speed at the same time.
People still have the naivete to trust things because they are on a screen. Preconceived notions cause one to mentally miss or gloss over the great artistry and manipulation in AVR cartoons.
The vid is worth the few minutes. It is a half decent scientific experiment that shows how rocket propulsion really works, and it shows an extra factor left out of the Newton's law argument: Ejective oxidation cannot occur without atmospheric containment pressure. Countless experiments have proven this. Buyer beware what they show you on a screen.
Can't reply to your other post unfortunately, but that's not true about rocket propulsion not working in a vacuum. You just have to mix the fuel with an oxidizer if oxygen isn't available. (EDIT: Or just use a method of propulsion other than combustion, but they are usually not as effective)
The helicopter is itself also a science instrument. How do they prevent any of the instruments from destroying each other? Careful planning, I would guess
[1] https://en.wikipedia.org/wiki/Ingenuity_(helicopter)